Need to raise a section over Ditra

[Danroonie]

New to the forum and need some advice on a floor leveling over Ditra.

Tore out a shower unit and converting to a curbless walk in shower using a kerdi drain. I padded out and leveled the floor outside the shower using modified thinset (since it's over plywood) - then applied Kerdi Ditra outside the shower. Unfortunately, when I dropped the shower floor to even it off with the Schulter shower tray - I discovered that the 2 x 12 joists were uneven - When I leveled that shower section, I now have the section outside the shower that is about 3/8" higher than the section right outside the shower. I'd like to raise the section outside the shower - what are my alternatives? I was considering using standard unmodified thinset (CustomBlend) on top of the ditra- letting it cure for a day minimal- then the same to set the floor tile. Was then going to use All-set for the wall tiles. Thoughts especially on leveling over Ditra? I was considering redgard on top of the raised thinset- but wondering if that is overkill since very little water will be outside the shower?

(Tiles: 12x24" x0.4" large format tiles with 1/8" grout lines on the floors and walls)

Thanks in advance!

 

[Jadnashua]

First, thinset is not designed to be used for leveling. It's called THINset for a reason. MOst of them aren't designed for more than about 1/4" or so. Going thicker results in shrinkage, and cracks in most cases.

Hindsight is damning...things that you thought were fine initially, look so funky after when the situation has changed.

The instructions for Ditra specifically say to deal with any leveling and flattening PRIOR to the installation of Ditra. The uncoupling ability of the material will change some if you end up with an over-thick layer of whatever on top of it prior to installing the tile.

While you might not want to hear it, your best bet is probably to tear up the Ditra, level/flatten the floor, and reinstall new. You might check out www.johnbridge.com where there are lots more tiling pros that might offer some other suggestions. You might also want to try to call Schluter's tech support line, but I don't know if there's anyone there. You might have to leave a message, and get a call back. NY is one of the states that asked companies to close for the duration.